Apparatus for the microdermal abrasion of the surface of tissue (living or dead) is well known. In these processes, a stream of abrasive particles such as sand is applied to the surface of the tissue or skin through an opening in a hand held tool (termed a handpiece) which is sealed against the skin. The tool and the particle stream is controllably scanned over the area to be abraded. The abrading particles and the removed tissue are then collected by vacuum in the handpiece and are passed through and collected by a filter to prevent the escape of the abraded tissue and sand into the vacuum pump and ambient atmosphere.
The handpiece has taken many forms in the past but usually provides a first passage for conducting abrasive particles from a reservoir to the area to be treated and a second parallel channel for conducting the particles and abraded skin away from the area treated and into a disposal vessel.
A typical prior art apparatus is shown in U.S. Pat. No. 5,037,432. The hand-held head of this patent is a long tubular structure having an off-center hole which permits the application of an abrasive particle jet to an area to be treated, and the subsequent removal of the particles and abraded skin. The off-center outlet hole is arranged to be on the same axis as the input abrasive particle jet which then reaches the area to be treated at a 45.degree. angle. The outlet jet channel facing the opening has a nozzle restriction. The abraded skin and used particles are then withdrawn through a parallel return vacuum channel which is connected to a vacuum pump through a filter.
The above described hand held tool has a number of drawbacks. Thus, because it is relatively long (longer than about 5 inches) it is difficult to manipulate easily over a curved surface area to be abraded, for example, the surface of a human face. Further, the vacuum pressure within the hand tool is not easily changed by the operator when a weaker or more forceful jet of abrasive particles is desired at particular locations on the surface area being abraded. Further, the handpiece is subject to clogging at the restricted outlet nozzle, requiring the operator frequently to stop the treatment and clear the nozzle.
The above described handpiece is provided with a removable and disposable tip or bell section which contains the output hole. Thus, the tip can be removed and disposed of and replaced by a new tip after the treatment of each individual. The tip is normally press-fit onto the body of the handpiece and is tightly sealed thereto to prevent accidental escape of abraded skin and loss of vacuum. Therefore, the tip is very difficult to remove and replace.
It would be very desirable to provide a handpiece for abrasion of living tissue which avoids the above problems.
The abrasive particles and tissue which are removed in prior art devices are collected in a filter placed between the handpiece outlet channel and the vacuum pump. Such a filtration system is shown in U.S. Pat. Nos. 5,100,412 and 5,207,234 in the name of Rosso. The filter shown therein is an inverted cup at the outlet opening of a waste receiving chamber. The outlet opening is connected to the vacuum pump line and contaminated particles and debris flow from the cup exterior toward its interior thus building up on the cup exterior. This filter tends to become quickly clogged and becomes more and more impervious to the flow of air therethrough. Consequently, the system must be frequently turned off and the filter must be cleaned sometimes during and frequently after each use.
It would be very desirable to provide a filtration system which does not require frequent cleaning or emptying.